The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
(1) Field of the Invention
The present invention relates to an improved system and method of steering marine vehicles, particularly personal water craft, that are propelled and maneuvered with water jets.
(2) Description of the Prior Art
In recent years, marine jet propulsion units have become popular for recreational water craft. Such units ordinarily have one or more propellers, which are driven within a tubular housing, for drawing water into the housing from one end and forcefully expelling the water at the other end to provide a driving force for the craft. In some units, the tubular housing itself is pivoted from one side to the other to provide steering. In other units, a deflector plate is provided at the exhaust end to deflect the jet flow to one side or the other of the craft.
A number of different steering systems have been used in connection with water craft. U.S. Pat. No. 3,982,493 to Cronin, for example, illustrates a skid control mechanism having longitudinally hinged flaps mounted to opposite sides of the boat bottom. The flaps are operable to deflect into an open, water-engaging position to prevent side slippage of the boat when making high speed turns. U.S. Pat. No. 4,004,536 to Bernier illustrates yet another anti-skid system in which an elongated vane extends along each side of the hull of the water craft.
U.S. Pat. No. 5,437,568 to Kobayashi illustrates a water jet propulsion system having an integrated rudder system.
U.S. Pat. Nos. 4,949,662 to Kobayashi and U.S. Pat. No. 6,086,437 to Murray illustrate steering systems for personal water craft. In the Kobayashi ""662 patent, the steering system includes a rudder carried by a forward portion of the hull, which rudder is out of the water at high speeds and submerged at low speeds for assisting in low speeding steering. The Murray patent relates to lied a blow back rudder consisting of a rudder blade, a rudder shaft and a plate assembly that is pivotally mounted to a jet nozzle. The plate assembly pivots the rudder shaft and the rudder blade away from the exhaust port of the jet nozzle and out of the water stream in the non-deployed position. A spring is attached to the rudder assembly and the water craft for positioning the rudder blade in the water when the velocity of the water stream ceases or decays.
Another system for steering a jet powered water craft at low speeds is shown in U.S. Pat. No. 3,976,026 to Eastling. In this system, the jet power unit of a water craft is provided with a steering plate which is deflectable upwardly but which is continuously oriented in the direction of, but spaced below, the flow of water from the jet. The jet power unit includes movable steering deflectors at its exhaust port which steer the craft by deflecting the jet flow to one side or the other. The steering plate includes a linkage system for pivoting the plate relative to the craft in response to movement of the jet deflectors to maintain the plane of the steering plate parallel to the direction of jet flow.
Water craft safety remains a high priority in the transportation industry and in federal, state, and local governmental agencies. Of more recent concern is the safety of the increasingly popular, water-jet powered personal water craft. According to the U.S. Coast Guard, such water craft account for 36% of the vessels involved in marine accidents. Such water craft can travel at speeds as high as 60 mph and rapidly spin 360 degrees in the water. In addition, water-jet powered personal water craft offer almost no physical protection to the rider. Because of these facts, control of water-jet powered personal water craft is a critical factor. A recent study by the National Transportation Safety Board and the United States Coast Guard has indicated that the lack of off-throttle steering is a contributing factor in many personal water craft accidents. In many such craft, the only steering ability is that provided by steering the thruster jet nozzle. When an inexperienced driver wants to stop suddenly to avoid an unexpected obstacle their first panic reaction is to let go of the throttle. When the throttle is off the vehicle has no steerage and thus proceeds straight into the obstacle.
Mechanisms that steer the personal water craft at low throttle do not currently exist on commercial models. Thus, there is a need for a steering system which operates when the throttle is let off and requires no additional action from the driver other than turning the handle bars.
Accordingly, it is an object of the present invention to provide a steering system for a water-jet propelled water craft.
It is a further object of the present invention to provide a steering system as above which is effective at low throttle speeds.
It is yet another object of the present invention to provide a steering system as above which may be operated by a driver by turning a standard steering device onboard the water craft.
It is yet another object of the present invention to provide an improved method of steering water craft.
The foregoing objects are attained by the steering system and method of the present invention.
A steering system for a water craft in accordance with the present invention broadly comprises at least two variable camber plates or rudders mounted to a hull of the craft for steering the craft, particularly at low throttle. Each of the plates has a leading edge which is affixed to the hull and a trailing edge. The steering system further comprises a linkage mechanism attached to an onboard steering device, such as a wheel or handle bars, for causing the trailing edge of at least one of the plates to move relative to the hull and thereby vary the camber of the at least one plate and impart a steering force to the craft. In a preferred embodiment of the present invention, each of the plates or rudders is formed from a flexible material.
A method for steering a water vehicle is also disclosed. The method broadly comprises the steps of mounting first and second variable camber rudders to a hull of the water vehicle and varying the camber of at least one of the rudders using a steering device on the vehicle to impart a steering force to said vehicle.